Problem with IP address and internet connectivity on second computer

O.K. not sure if the title is descriptive as to my problem, but here goes.

I have SBC DSL which is now AT&T. I have three computers connected to a SMC Barricade Router. So DSL in to DSL Modem, then to SMC Router, then to my computer (computer No. 1), computer number 2 and to computer number 3. all of which are plugged into the back of said Router. Router address 192.168.2.1 IPs 192.168.2.1xx and so on for each of the 3 computers.

Problem:

Yesterday I pulled computer No. 3 and replaced with a dell optiplex/optiflex GX240. This computer was empty, blank, no OS. So I installed XP and SP2 and O.K. it's running install Video drivers and such and it works fine. Has a built in ethernet thingy, so I plug in the cable from router and it shows it's trying to connect and such. I get the error that "local Network connection is limited or not working". The usual, hey your connection sucks. Now the odd thing is that I tried to repair the connection but it pops up a message that it could not complete when it was trying to get address. So I disable the onboard ethernet and put in a card I had sittin around. Yes it works, I pulled it from another computer and it was connected to internet and working. So, I boot and it trys to connect and same thing. Funny/odd thing is that I will disable each of these connections and I get the same error. So I go into the connection properties and set IP maually instead of the get IP automatically setting through the tcp/ip settings. The connection then seems connected but still no internet. I go to computer No.2 and look at settings there and I set everything the exact same. Automatic settings blah blah blah, and still crap. The one thing I saw was that when it is set to auotmatic address thingy I highlight the connection in Network Connections in Control Panel and on the left hand side where you can see the Details it shows some way off address that it has gottin automatically. Address shown is 169.254.67.132 not even close to the address it should get from the Router. So how do I fix this and get it to connect like the other computer did?

One other thing, I have MAC Address Control enabled on the Router. Now how do I find the MAC address for the new computer No.3? Maybe this is the problem and I need to change this so it sees the new 'puter and such? Or should I disable MAC Address Control?

One other thing, I have MAC Address Control enabled on the Router. Now how do I find the MAC address for the new computer No.3? Maybe this is the problem and I need to change this so it sees the new 'puter and such? Or should I disable MAC Address Control?